Compound archery bow

• US 5,678,529 A
• Filed: 06/07/1995
• Issued: 10/21/1997
• Est. Priority Date: 02/23/1981
• Status: Expired due to Term

• Current Assignee: Precision Shooting Equipment Incorporated
• Original Assignee: Browning Corporation (Prosteel Security Holdings Inc)
• Inventors: Larson, Marlow W.
• Primary Examiner(s): Ricci, John A.
• Application Number:
  US08/478,903
• Time in Patent Office: 867 Days
• Field of Search: 124/25.6, 124/900
• US Class Current: 124/25.6
• CPC Class Codes: F41B 5/10 Compound bows compound crossbows F41B5/123
• CPC Class Codes: F41B 5/105 Cams or pulleys for compound bows
• CPC Class Codes: Y10S 124/90 Limb tip rotatable element structure

Abstract

A compound bow carries eccentrics, each of which has a non-circular string groove with a geometric center removed from the axis of the eccentric and a take-up groove which is out of registration with the string groove about substantially the entire peripheries of the grooves. The two grooves are carried by respective sheaves rotatably joined through a hub which is itself rotatably connected to one of the sheaves.

Claims

1. In an archery compound bow including a handle member, two resilient limbs carried by and projecting oppositely substantially symmetrically from the handle member, pulley means mounted on the tip portion of each of the limbs for turning about an axis relative to the handle member, a bowstring extending between the two pulley means and a take-up cable engaged with each pulley means, the improvement comprising a said pulley means comprising an eccentric member including:

a first sheave element carrying a string groove for paying out a portion of said bowstring as it is pulled;

a hub element pivotally mounted eccentrically with respect to said string groove and including means for mounting said eccentric member on a said limb; and

a second sheave element carrying a take-up groove for winding cable as said bowstring is pulled, said second sheave element being rotatably mounted with respect to said hub, and said take-up groove being eccentric with respect to said hub.

2. In a compound archery bow including a handle, a pair of limbs extending from opposite ends of the handle, a pair of eccentrics mounted on axles at the respective distal ends of said limbs and a pair of cables, each anchored at one end to a respective limb and wrapped around the eccentric mounted at the opposite limb to provide a wound end and a strung end, said strung ends being connected to opposite ends of a bow string so that as the bow string is pulled away from its rest position near the handle through an intermediate peak drawn position towards the fully drawn condition of the bow, the eccentrics pivot on their respective axles to permit unwinding of the strung ends of the cables from the eccentrics and winding of additional cable following said wound ends onto said eccentrics, the improvement comprising:

a non-circular winding track in each of said eccentrics positioned to receive respective said wound ends of said cables, said winding tracks being configured so that as said bow string is pulled from its intermediate peak drawn position to wind additional cable following said wound ends on to said eccentrics, successive portions of said winding tracks receiving cable are located closer to the axles of said eccentrics, thereby reducing the effective diameters of said winding tracks at the drawn condition of the bow; and

an unwinding track of different configuration than said winding track in each of said eccentrics positioned for unwinding said strung ends;

wherein

said unwinding track is carried by a first sheave element;

a hub element is pivotally mounted eccentrically with respect to said first sheave element around a bushing element, said bushing element being pivotally mounted on a said axle; and

said winding track is carried by a second sheave element rotatably mounted with respect to said hub, said winding track being eccentric with respect to said hub.

3. An improvement according to claim 2 wherein said unwinding track is non-concentric with respect to said axle.

4. In a compound archery bow including a handle, a pair of limbs extending from opposite ends of the handle, a pair of eccentrics mounted on axles at the respective distal ends of said limbs and a pair of cables, each anchored at one end to a respective limb and wrapped around the eccentric mounted at the opposite limb to provide a wound end and a strung end, said strung ends being connected to opposite ends of a bow string so that as the bow string is pulled away from its rest position near the handle through an intermediate peak drawn position towards the fully drawn condition of the bow, the eccentrics pivot on their respective axles to permit unwinding of the strung ends of the cables from the eccentrics and winding of additional cable following said wound ends onto said eccentrics, an improved eccentric comprising:

a non-circular winding track positioned to receive a said wound end of said cables; and

an unwinding track both of different configuration and longer than said winding track for unwinding a said strung end;

wherein

said unwinding track is carried by a first sheave element;

a hub element is pivotally mounted eccentrically with respect to said first sheave element around a bushing element, said bushing element being pivotally mounted on a said axle; and

said winding track is carried by a second sheave element rotatably mounted with respect to said hub, said winding track being eccentric with respect to said hub.

5. An improvement according to claim 4 wherein said unwinding track is non-concentric with respect to said axle.

6. An eccentric for a compound bow comprising:

a wheel element mounted to pivot on an axis and carrying

a string groove with a periphery having a geometric center remote from said axis, said string groove being parallel a plane approximately normal said axis;

a hub element pivotally mounted eccentrically with respect to said string groove around a bushing element, said bushing element including a pivot hole concentric with said axis; and

a take-up groove with a periphery which is of a different shape than and non-concentric with the periphery of said string groove pivotally mounted on said hub element;

said wheel element being structured for paying out from said string groove a central stretch of a bowstring as said wheel element pivots on said axis from a rest position to a peak force position and then to a fully drawn position;

said wheel element further being structured for receiving onto said take-up groove an end stretch of the bowstring as said wheel element pivots on said axis from said rest position to said peak force position to said fully drawn position.

7. An eccentric according to claim 6 wherein said take-up groove is non-concentric with respect to said hub element.

8. An eccentric according to claim 7 wherein the majority of the periphery of said take-up groove is out of registration with the periphery of said string groove.

9. An eccentric according to claim 8 in combination with a handle, limbs and a bowstring assembled as a compound bow characterized by the force required to be applied to said bowstring to cause said wheel to pivot on its axis from its rest position increasing until said wheel pivots to its peak force position and decreasing as said wheel pivots thereafter to its fully drawn position.

10. In a compound archery bow including a handle, a pair of limbs extending from opposite ends of the handle, first and second wheel elements, each rotatably mounted to a distal end of one of said pair of limbs, and an elongated cable element, each end of said elongated cable element wrapped around said wheel elements to provide a wound end at each wheel element and a string segment extending to each of said wheels so that as said string segment is pulled away from its rest position through an intermediate peak drawn position towards the fully drawn condition of the bow, the eccentrics pivot to permit unwinding of the string segment ends of said cable element from the eccentrics and winding of additional cable element, the improvement comprising:

a wheel element mounted to one of said limbs and carrying

a string groove with a periphery having a geometric center remote from said axis, said string groove being parallel a plane approximately normal said axis;

a hub element pivotally mounted eccentrically with respect to said string groove around a bushing element, said bushing element including a pivot hole concentric with the pivot axis of said wheel element; and

a take-up groove with a periphery which is of a different shape than and non-concentric with the periphery of said string groove pivotally mounted on said hub element.